Impact of weight on daily activities questionnaire in patients with overweight or obesity: Psychometric evaluation using data from the OASIS 1 trial.

The Impact of Weight on Daily Activities Questionnaire (IWDAQ) is a patient-reported outcome measure that uses a novel, adaptive design to assess the limitations in daily activities that are most important to individuals attempting to lose weight. During the first round of completing the IWDAQ, respondents are presented with 18 everyday activities that can be limited by excess weight and asked to choose the three activities they would most like to see improve with weight loss. They are then asked to rate the degree of limitation they experience with these three activities at baseline and at follow-up assessments. Using data from a weight-management clinical trial (OASIS 1, NCT05035095), we evaluated the IWDAQ's measurement properties, determined optimal scoring, and estimated thresholds of meaningful within-patient change. Our analyses demonstrated that the IWDAQ Composite Score offers a reliable and valid personalized measure of limitations in daily activities due to excess weight. The adaptive design of the IWDAQ ensures the patient-centricity of the measure, thereby complementing existing measures of functioning in the context of weight-management clinical trials. Evaluations using data from additional studies would be valuable in extending the psychometric evidence for the IWDAQ.